Planetary transmission



Nov. 18, 1941. w. B. osBoRNE 2,262,959

PLANETARY TRANSM I S S ION NOV- 18, 1941 w. B. osBoRNE PLANETARY TRANSMISSION Filed Dec. Al1, 1939 2 Sheets-Sheet 2 m .U 7pm -'plates an improved arrangement -j-braking mechanism, v therein for developing torque vPatented Nov. 18, 1941 2,262,959 PLANETARY TRANSMISSION William B. Osborne, Muncie, Ind.,

Borg-Warner Corporation, Chicago,

poration of Illinois assignor to Ill., a cor- Application December 11,1939, Serial No. 308,624

(ci. 'r4-26o) 19 Claims.

This invention relates to planetary transmissions and has as its general object to provide a two-speed transmission particularly adaptable for aircraft propeller drive purposes. This application in part forms a continuation of my pending application Serial No. 213,968, led June 16, 1938, 'allowed July 17, 1939, now 2,189,220, for Planetary gear drive, and the entire dsiclosure of that application isincorporated herein by reference.

A primary object of the invention is to provide a transmission wherein a shift from one gear ratioto another may be eifected without passing through a neutral position, i. e., without releasing the driving connection between the driving and driven members at any point in the shift. This feature is 'particularly desirable in an airplane propeller drive.

More specifically, the invention contemplates the provision of a transmission adapted to transmit selectively from a driving to a driven member, either an underdx'ive or a direct drive, underdrive being effected by driving from the ring 'gear to the carrier of the planetary gearing, the sun gear being held stationary in order to establish the underdrive, and direct drive being effected by releasing the sun gear and simultaneously establishing a lock-up between at least two of the planetary members through the medium of a friction clutch.

The invention further contemplates the employment of centrifugal means for effecting the engagement of the clutch, and such centrifugal means is preferably arranged to respond tothe rotation ofthe sun gear, and is therefore vinoperative while the sun gear is restrained from rotation and is made operative when the sun gear is released and allowed to rotate.

A further object of the'invention is to provide,

. in a transmission of the character indicated above, means, operable in conjunction with the restraining of sun gear rotation, for rendering the centrifugal mechanism of the clutch inoperative so as to facilitate the'release of the clutch and thereby make it possible to reestablish the underdrive `following a period of direct drive operation.

4- ther object of the invention is to provide an improved braking' mechanismfor controlling the sun'gear. The invention further contemof sun gear 1 and means, incorporated centrifugal mechanism of the clutch inoperativel uponthe appli tion of the sun gear brake.

Another object of the invention is to provide an improved clutch arrangement for establish-4 is made for a direct lock up between the ring Patent No.

gear and the planetary carrier so as to bypass the gears, when the transmission is operating in direct drive.

Other objects, the advantages and uses of the invention will become more apparent after reading the following specification and claims and after consideration of the drawings forming a part of the specification, wherein:

Fig. l is a side elevation, partly in section, of a transmission embodying the invention;

Fig. 2 is a transverse sectional view thereof taken as indicated by the line 2-2 of Fig. 1; and

Fig. 3 is a transverse sectional view taken as indicated by the line 3-3 of Fig. l.

As an illustration of one form in which the invention may be embodied, I have shown in the drawings a planetary transmission particularly adapted for employment as a two-speed drive between the engine and propeller of anvairplane, comprising in general -a two-part housing 66, 61, driving and driven shafts 68, 69 adapted to be connected respectively to an engine and propeller of an airplane, a ring gear 10 attached to the drive shaft 68, a planet carrier 1l attached to the driven shaft 69, a sun gear 12, planet gears 13 journalled on the carrier and the meshing with the ring gear 10 and sun gear 12, a brake, indicated generally at 15, for locking the sun gear against rotation, and a clutch, indicated generally at 16 for locking the transmission in direct drive.

In general, the invention contemplates an arrangement wherein as the brake is released the clutch will become engaged and vice versa so that a drive will always be maintained from the driving shaft 68 to the driven shaft 69. This is important 1n aircraft construction, in order that the pilot may retainy full control over the propeller at all times.

In order to accomplish this general object, the clutch 16 is arrangedto be engaged by centrifugal mechanism carried by the sun gear `and when .the sun gear is released for rotation, the

' centrifugal mechanism will become operative and for rendering the the direct drive will thereupon be established.

The centrifugal elements, in the\\form of levers 11, having weighted ends 18, are pivoted on pins 1 9 'mounted in an annular plate ,80 which is Instead, provision 15, and will return to splined as at 8| to sun gear 12.

The levers 11 are formed with camming portions 83 adapted, as the weighted ends 18 move radially ou ardly, to exert radially inwardly the extended hub 82 of the directed pre sure against clutch shoes 84 through the medium of rollers 85 confined between the camming portions 83'and sockets 86 formed in the shoes 84. I'he shoes 84 are provided with friction facings 81 winch are adapted to simultaneously engage apair of axially adjacent clutch drums 88 and 89 carried by the planet carrier 1| and ring gear 10 respectively. v'I'hus when the clutch is engaged, a direct connection between the ring gear and carrier, bypassing the planet vlgear 13, lwill be established, and no torque will be transmitted through the gear teeth. The

shoes 84 are conned circumferentially betweenl lugs 90 formed on the sungear plate 80, and thus the sun gear also will be locked toA the ring gear and carrier by the operation of the clutch, although it is to be understood that this result is incidental to the direct lockup between the carrier and the ring gear whichv is particularly each roller is urged to one extremity of its socket by means of a compression spring 99.

The declutching ring 9| is normally main-Y tained in-its inoperative position by tension springs each having one end attached toga post 19 and its other end attached to a stud 0| fixed in the flange 98. K

'I'he ring is moved to its operative position by torque developed in the operation of the braking mechanism which will now be described.

Formed on the sun gear plate 80 is a brake drum |02. Formed on thel inner periphery of the flange 98 of the ring 9| is a brake drum |03, axially adjacent the drum |02. Mounted between lugs |04` formed in the housing 61 and projecting intoy the Aspace defined by the brake drum |02, area series of brake shoesI having friction facings |06 adapted to simultaneously engage the drums |02 and |03. ment with the drum |02 restrains the rotation of the sun gear. The engagement with the drum |03 shifts the declutching ring 9| to operative position wherein the levers 11 are cammed inwardly to release the clutch. Shoes |05 are narrower than the space between lugs |04 to allow for a slight relative circumferential movement between the lugs and shoes. A spring |33 .nor-

' mally biases the shoes |05 in a counter-clockwise relied v rect' drive, for the reason that the engagement v of the clutch constrains" the sun gear to rotate along with the other rotatingsparts, and the rotation of the sun gear maintains the clutch in engagement.

It is important that .provision be made for shifting the transmission from direct back to underdrive without arrestingthe drive through the transmission. In the operation of an airplane, emergencies may arise in the air or in landing, making it desirable for the pilot to go into a sudden climb, and therefore requiring the reestabllshment of underdrive. In order to meet this problem, the neutralizing or opposing the centrifugal action of the levers 1.1 sufficiently to allow the clutch to slip as the brake 1.5 is applied.

Such declutching mechanism comprises a declutching ring 9| having a series of circumferdirection as viewed in Fig. 2. A tongue-and groove connection |34 provides a positive lock be' tween the friction facings |06 and shoes |05 to cause the latter to move with the facings. This constructionprovides a servo-action for the brake shoes which. makes it possible to arrest the rotation of the sun gear with the. application of a smaller force than would otherwise be necessary..

The brake shoes |05 are lar cam ring |01 ing rollers |09 conilned in sockets ||0 in the respective shoes.

actuated by an annu- 'The cam ring 01 is formed with a portion of reduced diameter journalled in a shoulder formed in the housing 61. Movement of the ring invention provides means for entially elongated apertures 92 througl-fwhich the lever fulcrum pins 19 extend, and having a series of cam projections 93 adapted, as it moves from one extremity to the other of its lost motion connection formed by the pins 19 and slots 92, to engage inclined cam faces 94 on the weighted ends 18 of the levers, and weighted ends inwardly so as to release the clutch. The inward movement of the weighted ends ofthe levers is assisted by coil springs 98 interposed between the weighted ends rim 91 of the ring 9|. point that the ring 9| and the It may be noted at this is L-shaped in crossforce said` section, including the rim ange 91 and the raa rolling one, inorder to mini- |01 may be effected by a manual control includingv an eccentric |2 having a shaft portion |3 journalled in the housing 611 and an eccentric pin ||4 engaged in a notch ||5 in the ring |01.

The planet gears 13 are ||6 mounted'in the carrier 1.|. drum 88 is formed on an annular plate ||1 mounted on the pins H6,- being connected to the plate ||1 by a sleeve |8 extending through the open drum 89 ofthe ring gear. The drum 89 is formed 'on an annular plate ||9 having an internally splined engagement |20 with the ring gear 10. 'I'he plate ||9 cooperates with journalled on pins the sun gear plate in forming an annular space in which the clutch shoes 18 are mounted for radial sliding movement between the lugs 90.

mounted in the housing member 66. The driven shaft 69 is piloted in the .shank '|23 as by means of roller bearings |28. Thecarrier 1| may be connected to the driven shaft 69. by means of a spline connection |21. 4The hub portion 82 of= the sun gear is preferably journalled upon the The engagehaving cam faces |08 engag-` The carrier clutch ltion of the already rotating Y, aaeaeto drive shaft ss as by means of bearings m. The

driven shut B may be journalled in the housing member 61 by means of a roller bearing |29. The sun gear assembly is maintained against axial displacement by a thrust bearing |30 interposed between the end of the sun gear hub v82 and an abutment ring |3|jengaged against a shoulder |32 formed in the driven shaft 69.

In: the operation of the transmission, when embodied in an airplane for example, the underdrive gear ratio may be established prior to starting the engine by rotating the manual control eccentric ||2 so as to move the ring |01 to the position in which it cams the brake shoes |05 outwardly into engagement with the brake drum |02. The brake drum |03 will also be engaged but without effect upon the declutching ring 9| for the reason that the springs |00 will hold the latter in its inoperativeposition. The engagement of the brake drum |02 locks the sun gear 12 against rotation.

from the drive shaft B8 to the ring gear 10 and thence through the planet gears 13 tothe carrier 1|, the Aplanet gears 13 tracking against the stationary sun gear 12 so as to deliver drive to the carrier at areduced rate of speed as compared to that of the driving shaft. 'Ihe speed reduction will give a` corresponding increase in torque which is utilized to overcome the heavier loads imposed upcn the propeller in the take oif and climb for elevation. When the pilot desires to level off for horizontal iiight, he rotates the control eccentric ||2 in a reverse direction so as to release the brake and allow the sun gear to commence ,rotating under the torque reaction of the planet gears 13. By momentarily 'decelerating the engine, the planet carrier may be caused to become the driving member and the ring -gear the reaction member, and the resulting direction of thrust of the planet gears against the sun gear will be the same as the direction of rotaring gear and planet carrier. w Y

The rotation of the sun gear, thus initiated, will cause the weighted levers 11 to fly outwardly, camming the clutch shoes 0I radially inwardly into clutching engagement with the clutch drums 88 and 09 respectively. As soon asthe clutch becomes engaged, rotation will be trans- -mitted to the sun gear from the ring -gear and carrier, thus maintaining the centrifugal elements energized and the clutch engaged. Ac-

cordingly, the ring gear, carrier and sun gear will remain locked together as long as the drive shaft continues to rotate at a sufficient speed to energize the centrifugal elements. In the event that the pilot desires to shiftback to underdrive while in the air, he simply rotates the con trol eccentric ||2 to brakeengaging position, causing the brake shoes |05 .to be forced outwardly against the brake drum |02 and the drum |03. In its initial stage, the braking engagement against the brake drum |02 will .be ineffective to restrain the rotation of the sun gear, for the reason that the clutch will remain engaged as long as the sun gear is rotating at a sumcientspeed, and the sun gear will continue to rotate as long as the clutchV is engaged and the drive shaft is driving. However, the engagement against the drum |03 will be immediately effective. The `declutching ring 9|, which has 'been' rotatingalong with the gear, under the pull of the springs |00,-will be mo- As a result, when Y the engine is started, drive will be transmitted lill mentarily retarded suiiiciently to move it to the opposite extremity of its lost motion connection against the pull of the springs |00 and in so moving, it will render the centrifugal levers 11 inoperative by the camming engagement of its cam projections 93 with the cam faces 94 of the levers. Thus the clutch is released, and the braking action against the brake drum |02 will become effective to arrest the rotation of the sun gear and thereby reestablish the underdrive.

Engagement of the brake will assure the release of the clutch under all conditions. If the transmission-is operating, the release will be effected by the camming mechanism in the manner described above. If the transmission is not operating, the camming mechanism of course will be ineffective as a result of the springs |00 returning the declutching ring to its inoperative position, but in this case the springs ,96 will move the clutching levers inwardly to their inoperative position, thereby assuring full clutch release.

While I have described my invention in connection with one specific embodiment thereof, it is to be understood that this is by way of illustration and not by way of limitation and the scope of my invention is dened solely by the appended claims which should be construed as broadly as the .prior art will permit.

I claim: e

l. In a planetary transmission, in combination with a sun gear, a carrier, planet gears on the carrier meshing with the sun gear, and a ring gear adapted to underdrive the carrier through the planet gearsV when rotation of the sun gear is restrained, a centrifugal clutch adapted to lock the ring gear to the carrier and to thereby establish direct drive through the transmission, a brake adapted to lock the sun gear against rotation to establish underdrive, means for controlling the operation of the brake, and means, operated by said brake operating means during the sun gear locking operation, for neutralizing .the centrifugal action of said clutch so as to release said direct drive and thereby facilitate the establishing of underdrive following direct -drive operation.

2. In a planetary transmission, yin combination with planetary elements including a sun gear,

. a carrier, planet gears and a ring gear in planetary relation to each other, with the ring gear adapted to underdrive the carrier when rotation of the sun gear is restrained, a centrifugal clutch adapted to lock two of said elements together so as tov establish a direct drive through the transmission, a brake for restraining the sun gear, means for controlling the operation of the brake, and means, operated by said brake oper-- ating means, during such restraining operation, for opposing the centrifugal action of said clutch so as to facilitate vthe release of said direct drive and the establishing of underdrive following direct drive operation.

3. In a planetary transmission, in combination with planetary elements including a sun gear, a carrier, planet gears and a ring gear in planetary relation to each other, a centrifuga-l clutch adapted to lock at least two of said elements together so as to establish a direct drive through said transmission, a brake adapted to restrain rotation of one yof said elements so as to establish a drive of another ratio through said'transmission, means for controlling theoperation of the brake, and means, operated by said brake operating means during braking action upon said one element, for opposing the centrifugal action of said clutch so asto facilitate the'release of said direct drive and the establishing of the other drive following direct drive operation.

4. In a planetary transmission, in combination withv planetary elements including a sun gear, a carrier, planet gears and a ring gear in planetary relation to each other, with the ring gear adapted to underdrive the carrier when rotation of the.

sun gear is restrained, a centrifugal clutch having centrifugal members responsive to sun gear rotation, adapted to lock at least two of said elements vtogether so as to establish a direct drive throughthe transmission, a brake for restraining the sun gear, and means, operable in conjunction with the brake during such restraining operation, for moving said centrifugal members to inoperasun gear is restrained, a centrifugal clutch hav 4 ing centrifugal members responsive to sun gear rotation, adapted to lock two of said elements together so as to establish' a direct drive through carrier, planet gears and a ring gear in planetary tive positions so as to facilitate the release of said f ed to lock two of said elements together so as to establish a directdrive through the transmission, a brake for restraining thelsun gear, and means, rotatable with one of said elements, engaged by said brake during the sun gear restraining operation and adapted, under torque developed by its engagement with the brake, to oppose the centrifugal action of the clutch so as to facilitate the release of said direct drive and the establishing of underdrive following direct drive operation.

6. In a planetary transmission, in combination with planetary elements including a sun gear, a carrier, planet gears and a ring gear` in planetary relation to each other, with the nng gear adapted to underdrive the carrier when rotation of the sun gear is restrained, a centrifugal clutch adapted to lock two of said elements together so'as to establish a direct drive through the transmission, a brake for restraining the sun gear, and means, having a lost motion connection with one of said elements, engaged by said brake during the sun gear restraining operation, adapted to be moved by such brake engagement, and arranged to render the centrifugal mechanism of the clutch inoperative as a result of such movement.

7. In a planetary transmission, in combination with a sun gear, a carrier, planet gears on the 1 carrier meshing with the sun gear, and a ring gear adapted to underdrive the carrier through theplanet gears when rotation of the sun gear is restrainedfa centrifugal clutch adapted to lock the ring gear to the carrier and to thereby establish direct drive through the transmission, a

brake adapted to lock the sun gear against rotation to establish underdrive, and means, having a lost motion drive connection with the sun gear,

\ engageable by said brake during the sun gear restraining operation, adapted to be moved by said brake engagement, and arranged to render the centrifugal mechanism of the clutch inoperative and means, operated by the manual means, for

as aresult of such movement, so as to facilitate the establishing of underdrive following direct drive operation.

8. In a planetary transmission, in combination with planetary elements including a vsun gear,a carrier, planet gears and a ring gear in planetary relation to-each other, with the vring gear adapted to underdrive the carrier when rotation of the the transmission, a brake for restraining the sun gear, and a declutching ring having a lost motion driving connection with the sun gear, adapted to be engaged by the brake during the sun gear restraining operation, to be thereby moved and, in thus moving, to engage the centrifugal members and move them to inoperative positions so as to facilitate the release of the direct drive and the establishing of underdrive followingdirect drive operation.

9. In a planetary transmission, in combination I with planetary elements including a sun gear, a

relation to each other, a centrifugal clutch adapted to lock at least two of said elements together so as to establish a direct drive through said transmission, said clutch including centrifugal members responsive to rotation of one of said elements, a brake adapted to restrain rotation of one of said elements s o as to establish a drive of another ratio through said transmission, means for controlling the operation of the brake and a declutching ring, having Aa lost-motion connection with one of said elements, adapted to be moved from one to another position of said Y clutchadapted to'lock at least two of said ele- `lishing of the other drive following ments together so as to establish a direct drive through said transmission, said clutch including Acentrifugal members responsive to rotation of r vone of said elements, a brake ,adapted to restrain rotation of said one element so as to establish a drive of another ratio throughsaid transmission, and a declutching ring having a lost motion connection with said one element, adapted to be moved fromone to another position of said lost motion connection byy torque developed in the restraining operation, and, during such movement, tov engage the centrifugal members and kmove them to inoperative positions so as to facilitate therelease of the direct drive and the estabdirect drive operation. r

1l. In a planetary transmission, in combination with planetary elements including a sun gear, a carrier, planet gears and a ring gear in planetary relation to each other, with the ring gear adapted/to underdrive the carrier when rotation of the sun gear is restrained, a centrifugal clutch adapted to.lock two of said elements together so as' to establish a direct drive through the transmission, a bralgefor restraining the sun gear, manual means for controlling the brake,

opposing the centrifugal action of said clutch so cent clutch drums carried by said carrier andv ring gear respectively, a clutching shoe associated with the sun gear and adapted to engageV said drums for locking all of said elements together for direct drive, centrifugal members carried by the sun gear, for operating said clutching shoe at a predetermined speed of sun gear rotation, a brake for restraining rotation ofthe sun gear, and a declutching member, carried by the sun gear and acted upon by the brake during the sun gear restraining operation, so as to oppose the action of the centrifugal members, whereby to facilitate the reestablishment of underdrive following a period of direct drive operation.

13. In a planetary transmission, a housing, planetary elements therein comprising a sun gear, a carrier and a ring gear in planetary' relationship, with the ring gear 'adapted to underdrive the carrier when rotation of the sun gear is restrained, a centrifugal clutch, responsive to sun gear rotation, adapted to lock said elements in direct drive, a brake drum carried by the sun gear, a braking shoe associated with the housing and engageable with said drum for restraining sun gear rotation,and a declutching ring having a lost motion connection with the sun gear, having a part adapted to be engaged by said shoe when the latter engages the drum, whereby to move said ring relative to the ring gear, and adapted, when thus moved, to oppose the centrifugal action of the clutch so as to facilitate the reestablishment of underdrive. y Y

i4. In a planetary transmission, a housing, planetary elements therein comprising a sun gear, a carrier and a ring gear in planetary relationship, with the ring gear adapted to under drive the carrier when rotation of the sun gear is restrained, a centrifugal clutch, including centrifugal members carried by thesun gear and adapted, in response to sun gear rotation, to lock said elements in direct drive, a brake drum carried by the sun gear, a brake shoe associated with the housing and engageable with said drum for restraining sun gear rotation, and a declutching ring having a lost motion connection with the sun gear, having apart adapted to be engaged by said shoe when the latter engages the drum, whereby to move said ring relative to the ring gear, and having parts adapted, when thus moved, to exert a camming action against said centrifugal members so asfto render them inoperative and thereby facilitate the'release of the clutch and the consequent establishment of underdrive.

' 15. A planetary transmission as dened in claim 13, including a ring, rotatable with reference to the housing, having a cam element adapted, when rotated, to move said brake shoe into braking position.

16. A planetary transmission as deiined in claim 13, including an operating ring, rotatable with reference to the housing, having a cam element, adapted, when rotated, to move said brake shoe to braking position and a manually operable eccentric journalled in the housing and cooperating with said operating ring for rotating the same.

17. In a planetary transmission, a housing, planetary elements therein including a ring gear, a carrier and a sun gear in planetary relation to each other, axially adjacent clutch drums attached to the ring gear and carrier respectively, a brake drum attached to the sun gear, a clutch shoe having a radially movable, corcumferentially xed association with said brake drum, a weighted lever pivoted on the brake drum and coacting with the clutch shoe to establish clutching engagement with .both of said clutch drums whereby to lock said elements in direct drive, a declutching ring having a lost motion connection with said brake drum, a drum portion on said declutching ring axially adjacent said brake drum, a brake shoe adapted to simultaneously engage said brake drum and drum portion for restraining sun gear-v rotation and causing said declutching ring' to move relative to the brake drum, said ring havinga part adapted, when thus moved, to exert a camming action against said lever so as to render the samevinoperative whereby to facilitate release of the clutch and the establishment of underdrive.

18. In a planetary transmission, the combination described in claim 5, said brake being a servo-acting brake.

19. In a planetary transmission, the combination described in claim 5, said brake comprising a rotatable drum, brake shoes for cooperating with the drum, wedge means for urging the shoes against the drum, and means permitting a limited relative movement between the wedge 'means and shoes under thel influence of the drum to increase the' wedg'lng action.

WILLIAM B. OSBORNE. 

